A gang of railway workers saw a UFO for ten minutes, to the South of the railway line. It appeared to be "hovering" and was silver in colour, reflecting the Sun's rays. It disappeared with a flash. There was no sound associated with the visual observation.

8 May 1966 Whittlesea, Victoria 1015hrs 10 minutes duration

A flying instructor saw an object at 30 degrees azimuth, 20 nautical miles at an estimated height of 8,000 feet. It was silver in colour. Through binoculars it seemed "...some sort of metallic substance..." In shape it was "Elliptical with dark core." There was no sound. It was initially stationary but descended to approximately 4,500 feet before being lost behind cloud.

17 May 1967 Thomastown, Victoria 1200hrs 60 minutes duration

A man reported using binoculars to watch a star-like flashing object high in the sky to the North West. It was in clear sky, had a round shape, and was noiseless. It seemed to be very high up in the sky. It was moving slowly to the South East, travelling in a straight line.

Five nursing sisters, on a clear day, saw an object high up in the sky, slightly North West of overhead. Light glinted on the object. They questioned whether it was a balloon. It was silver in colour, had a round shape and was soundless. It seemed to be "hovering" then moved North North West. It was lost to view "...up into the stratosphere."

A witness reported seeing a circular, shiny, white object. Initially it was observed due North moving South for 45 minutes, then moving West at very slow speed at high altitude. Total duration of the observation was three hours.

29 Aug 1969 Amberley, Queensland 1335hrs

There were numerous reports of a "balloon-like" object to the South. A Canberra aircraft located a balloon over Milmerran at 6,000 feet. Later it was revealed by the Balloon Launching Project at Mildura that they had launched a balloon on 25 August which failed to self-destruct and which then floated over South East Queensland.

10 May 1988 Bandendone, Queensland 1325hrs 20 minutes duration

A witness was travelling by car, when they saw an object in the sky, reflecting "metal-like" in the sunlight. There was no sound. It appeared to be "hovering" before rising steadily as it travelled East. An Exite x-ray telescope was launched by balloon from Alice Springs on this day.

My comment:

There certainly would appear to be UFO reports in the RAAF UFO files which fit being observations of stratospheric balloons. Interestingly, I cannot recall reading anything about this possibility in the files of Australian UFO research groups.

I would imagine that a diligent search of the reports archives of Australian groups would reveal further observations whose origin lie with stratospheric balloons. Unlike Operation Crowflight aircraft producing some UFO reports in the period 1960-1966; stratospheric balloon launches continue in Australia today.